『Abstract
　A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In a field monitoring, ammonium (NH4⁺) decreased from 4.6 to 1.7 mg L^-1, nitrate (NO3^-) decreased from 6.8 to 5.3 mg L^-1, total N (TN) decreased from 14.6 to 10.1 mg L^-1, and total P (TP) decreased from 1.6 to 1.1 mg L^-1. Average removal efficiencies (loading basis) for NO3^-, NH4⁺, TN, and TP were over 70％. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH4⁺. Results from mesocosm experiments indicated that NH4⁺ was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO3^-) was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2-4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH4⁺ and P can be maximized in the pond while NO3^- requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal if N and P from effluents of a secondary wastewater treatment plant.

Keywords: Constructed wetlands; Nitrogen; Phosphorus; Secondary treatment effluent』

1. Introduction
2. Materials and methods
　2.1. Constructed wetland description and water sampling
　2.2. Mesocosm experiments
　2.3. Water analysis　
　2.4. Calculations and statistical analysis
3. Results
　3.1. Nutrients and organic carbon removal in the mesocosms
　3.2. Water characteristics and nutrient removal in a pond-marsh wetland system
4. Discussion
　4.1. Nutrient removal efficiency in the pond-marsh wetland system
　4.2. Major factors for nutrient removal in the pond-marsh wetland system
　4.3. Applicability of a pond-marsh wetland system for treating effluents from secondary wastewater treatment plants
Acknowledgments
References